Figure 7.

Genetic deletion of eEF2K specifically disrupts contextual and trace fear-conditioning formation. (A,B) eEF2K-KO mice display normal CTA memory compared with WT animals in both weak (0.075 M LiCl) and strong (0.14 M LiCl) protocols. eEF2K-KO (n = 9), WT (n = 13) for both protocols. Error bars are SEMs. Student's t-test; P > 0.05. (C) eEF2K-KO mice display normal Morris water maze (MWM) learning. Escape latency was measured across 4 days of MWM task and shows that eEF2K-KO mice acquired the spatial learning same as control animals. eEF2K-KO (n = 5), WT (n = 7). Error bars are SEMs. Repeated-measures ANOVA, P > 0.05. (D) eEF2K-KO mice show normal spatial memory in Morris water maze probe test. Mice were trained using a standard Morris water maze paradigm and tested for spatial memory of platform location in the probe test. Results are displayed as percentage of time spent in each quadrant during the probe test. eEF2K-KO (n = 5), WT (n = 7). Error bars are SEMs. Student's t-test; P > 0.05. (E) Fear conditioning behavior procedure. Mice received 7 combinations of [tone interval shock] in context A using strong trace fear-conditioning protocol. For weak delay fear-conditioning protocol, mice received 1 trial composed of 2 pairings of tone shock in context A. Tests were done 24 h following conditioning. Context test was performed in context A, and the tone test was performed in context B. (F) Trace fear conditioning is impaired in eEF2K-KO compared with WT mice. Mice were exposed to the same trial of the conditioning but without shock in a novel context. Freezing, considered as “trace fear conditioning,” was measured during the time window between consecutive tones. Average of the first 4 traces is presented and analyzed, as they were less likely to be affected by extinction. eEF2K-KO (n = 8), WT (n = 8). Error bars are SEMs. Repeated-measures ANOVA, P < 0.05. (G) Long-term auditory fear conditioning is normal in eEF2K-KO mice using trace fear-conditioning protocol. Mice were exposed to the same tone that was delivered in the conditioning trial in a novel context. Seven presentations of the tone were given as the conditioning trial, 20 s each. Percentage of freezing was calculated during the tone presentation and average of the first 4 tone periods is presented and analyzed, as they less likely to be affected by extinction. eEF2K-KO (n = 8), WT (n = 8). Error bars are SEMs. Repeated-measures ANOVA, P > 0.05. (H) Long-term contextual fear conditioning is normal in eEF2K-KO mice using trace fear-conditioning protocol. On the contextual fear-conditioning test, animals were returned to the same chamber of training 24 h after training for 300 s without tone. Long-term contextual fear memory was measured as percentage of time spent freezing during the test trial. eEF2K-KO (n = 8), WT (n = 8). Error bars are SEMs. Student's t-test; P > 0.05. (I) Long-term contextual fear conditioning is impaired in eEF2K-KO mice using delay fear-conditioning protocol. On the contextual fear-conditioning test, animals were returned to the same chamber of training 24 h after training for 300 s without tone. Long-term contextual fear memory was measured as percentage of time spent freezing during the test trial. eEF2K-KO (n = 11), WT (n = 10). Error bars are SEMs. Student's t-test; P < 0.05. (J) Long-term auditory fear conditioning is normal in eEF2K-KO mice using delay fear-conditioning protocol. Mice were exposed to the same tone that was delivered in the conditioning trial in a novel context. Three presentations of the tone were given as the conditioning trial, 20 s each. Percentage of freezing was calculated during the tone presentation, and average of the tone periods is presented and analyzed. eEF2K-KO (n = 11), WT (n = 10). Error bars are SEMs. Repeated-measures ANOVA, P > 0.05.